@page "/design/templates"
@page "/design/templates/{TemplateIdParam:int}"
@using ScadaLink.Security
@using ScadaLink.Commons.Entities.Templates
@using ScadaLink.Commons.Interfaces.Repositories
@using ScadaLink.Commons.Types.Enums
@using ScadaLink.TemplateEngine
@using ScadaLink.TemplateEngine.Services
@using ScadaLink.TemplateEngine.Validation
@using ScadaLink.TemplateEngine.Flattening
@attribute [Authorize(Policy = AuthorizationPolicies.RequireDesign)]
@inject ITemplateEngineRepository TemplateEngineRepository
@inject TemplateService TemplateService
@inject TemplateFolderService TemplateFolderService
@inject AuthenticationStateProvider AuthStateProvider
@inject NavigationManager NavigationManager

<div class="container-fluid mt-3">
    <ToastNotification @ref="_toast" />
    <ConfirmDialog @ref="_confirmDialog" />

    <RenameFolderDialog @bind-IsVisible="_showRenameFolderDialog"
                        FolderId="_renameFolderId"
                        InitialName="@_renameFolderInitialName"
                        ErrorMessage="@_renameFolderError"
                        OnSubmit="SubmitRenameFolder" />

    <NewFolderDialog @bind-IsVisible="_showNewFolderDialog"
                     ParentFolderId="_newFolderParentId"
                     ErrorMessage="@_newFolderError"
                     OnSubmit="SubmitNewFolder" />

    <NewTemplateDialog @bind-IsVisible="_showNewTemplateDialog"
                       FolderId="_newTemplateFolderId"
                       ErrorMessage="@_newTemplateError"
                       OnSubmit="SubmitNewTemplate" />

    <MoveTemplateDialog @bind-IsVisible="_showMoveTemplateDialog"
                        TemplateId="_moveTemplateId"
                        TemplateName="@_moveTemplateName"
                        FolderOptions="EnumerateFolderOptions()"
                        ErrorMessage="@_moveTemplateError"
                        OnSubmit="SubmitMoveTemplate" />

    @if (_loading)
    {
        <LoadingSpinner IsLoading="true" />
    }
    else if (_errorMessage != null)
    {
        <div class="alert alert-danger">@_errorMessage</div>
    }
    else
    {
        <div class="row g-2">
            <div class="col-md-4 col-lg-3">
                <h6 class="mb-2">Templates</h6>
                <div class="btn-group btn-group-sm w-100 mb-2">
                    <button class="btn btn-outline-secondary" title="New folder at root"
                            @onclick="() => OpenNewFolderDialog(null)">+ Folder</button>
                    <button class="btn btn-outline-secondary" title="New template at root"
                            @onclick="() => OpenNewTemplateDialog(null)">+ Template</button>
                    <button class="btn btn-outline-secondary" @onclick="() => _tree.ExpandAll()">Expand</button>
                    <button class="btn btn-outline-secondary" @onclick="() => _tree.CollapseAll()">Collapse</button>
                </div>

                <div style="max-height: calc(100vh - 160px); overflow-y: auto;">
                    <div class="templates-root-dropzone"
                         @ondragover:preventDefault="true" @ondrop="OnDropOnRoot"
                         style="min-height: 100%; padding: 4px;">
                        <TreeView @ref="_tree" TItem="TmplNode" Items="_treeRoots"
                                  ChildrenSelector="n => n.Children"
                                  HasChildrenSelector="n => n.Kind != TmplNodeKind.Composition && n.Children.Count > 0"
                                  KeySelector="n => (object)n.Key"
                                  StorageKey="templates-tree"
                                  Selectable="true"
                                  SelectedKeyChanged="OnTreeNodeSelected">
                            <NodeContent Context="node">
                                @RenderNodeLabel(node)
                            </NodeContent>
                            <ContextMenu Context="node">
                                @RenderNodeContextMenu(node)
                            </ContextMenu>
                            <EmptyContent>
                                <span class="text-muted fst-italic">No templates yet. Use the buttons above to create a folder or template.</span>
                            </EmptyContent>
                        </TreeView>
                    </div>
                </div>
            </div>

            <div class="col-md-8 col-lg-9">
                @if (_selectedTemplate == null)
                {
                    <div class="text-muted fst-italic mt-3">
                        Select a template on the left to view or edit.
                    </div>
                }
                else
                {
                    @RenderTemplateDetail()
                }
            </div>
        </div>
    }
</div>

@code {
    private async Task<string> GetCurrentUserAsync()
    {
        var authState = await AuthStateProvider.GetAuthenticationStateAsync();
        return authState.User.FindFirst("Username")?.Value ?? "unknown";
    }

    [Parameter] public int TemplateIdParam { get; set; }

    private List<Template> _templates = new();
    private List<TemplateFolder> _folders = new();
    private Template? _selectedTemplate;
    private List<TemplateAttribute> _attributes = new();
    private List<TemplateAlarm> _alarms = new();
    private List<TemplateScript> _scripts = new();
    private List<TemplateComposition> _compositions = new();

    private bool _loading = true;
    private string? _errorMessage;
    private string _activeTab = "attributes";

    // Edit properties
    private string _editName = string.Empty;
    private string? _editDescription;
    private int _editParentId;

    // Validation
    private bool _validating;
    private Commons.Types.Flattening.ValidationResult? _validationResult;

    // Member add forms
    private bool _showAttrForm;
    private string _attrName = string.Empty;
    private string? _attrValue;
    private DataType _attrDataType;
    private bool _attrIsLocked;
    private string? _attrDataSourceRef;
    private string? _attrFormError;

    private bool _showAlarmForm;
    private string _alarmName = string.Empty;
    private int _alarmPriority;
    private AlarmTriggerType _alarmTriggerType;
    private string? _alarmTriggerConfig;
    private bool _alarmIsLocked;
    private string? _alarmFormError;

    private bool _showScriptForm;
    private string _scriptName = string.Empty;
    private string _scriptCode = string.Empty;
    private string? _scriptTriggerType;
    private string? _scriptTriggerConfig;
    private bool _scriptIsLocked;
    private string? _scriptFormError;

    private bool _showCompForm;
    private int _compComposedTemplateId;
    private string _compInstanceName = string.Empty;
    private string? _compFormError;

    private ToastNotification _toast = default!;
    private ConfirmDialog _confirmDialog = default!;

    protected override async Task OnInitializedAsync()
    {
        await LoadTemplatesAsync();
        if (TemplateIdParam > 0)
        {
            await SelectTemplate(TemplateIdParam);
        }
    }

    private bool _revealApplied;

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!_revealApplied && TemplateIdParam > 0 && _tree != null)
        {
            _revealApplied = true;
            await _tree.RevealNode($"t:{TemplateIdParam}", select: true);
        }
    }

    private async Task LoadTemplatesAsync()
    {
        _loading = true;
        try
        {
            _templates = (await TemplateEngineRepository.GetAllTemplatesAsync()).ToList();
            _folders = (await TemplateEngineRepository.GetAllFoldersAsync()).ToList();
            BuildTemplateTree();
        }
        catch (Exception ex)
        {
            _errorMessage = $"Failed to load templates: {ex.Message}";
        }
        _loading = false;
    }

    private enum TmplNodeKind { Folder, Template, Composition }

    private record TmplNode(
        string Key,
        TmplNodeKind Kind,
        int EntityId,
        string Label,
        int? ParentFolderId,
        int? OwnerTemplateId,
        Template? Template,
        TemplateComposition? Composition,
        List<TmplNode> Children);

    private List<TmplNode> _treeRoots = new();

    private void BuildTemplateTree()
    {
        // 1. Folder nodes keyed by id
        var folderNodes = _folders.ToDictionary(
            f => f.Id,
            f => new TmplNode(
                Key: $"f:{f.Id}",
                Kind: TmplNodeKind.Folder,
                EntityId: f.Id,
                Label: f.Name,
                ParentFolderId: f.ParentFolderId,
                OwnerTemplateId: null,
                Template: null,
                Composition: null,
                Children: new List<TmplNode>()));

        // 2. Attach folder nodes by ParentFolderId
        var roots = new List<TmplNode>();
        foreach (var f in _folders.OrderBy(f => f.Name, StringComparer.OrdinalIgnoreCase))
        {
            var node = folderNodes[f.Id];
            if (f.ParentFolderId is int pid && folderNodes.TryGetValue(pid, out var parent))
                parent.Children.Add(node);
            else
                roots.Add(node);
        }

        // 3. Template nodes with composition leaves
        foreach (var t in _templates.OrderBy(t => t.Name, StringComparer.OrdinalIgnoreCase))
        {
            var compChildren = t.Compositions
                .OrderBy(c => c.InstanceName, StringComparer.OrdinalIgnoreCase)
                .Select(c => new TmplNode(
                    Key: $"c:{c.Id}",
                    Kind: TmplNodeKind.Composition,
                    EntityId: c.Id,
                    Label: c.InstanceName,
                    ParentFolderId: null,
                    OwnerTemplateId: t.Id,
                    Template: null,
                    Composition: c,
                    Children: new List<TmplNode>()))
                .ToList();

            var tNode = new TmplNode(
                Key: $"t:{t.Id}",
                Kind: TmplNodeKind.Template,
                EntityId: t.Id,
                Label: t.Name,
                ParentFolderId: t.FolderId,
                OwnerTemplateId: null,
                Template: t,
                Composition: null,
                Children: compChildren);

            if (t.FolderId is int fid && folderNodes.TryGetValue(fid, out var parentFolder))
                parentFolder.Children.Add(tNode);
            else
                roots.Add(tNode);
        }

        // 4. Sort each level: folders before templates, alphabetical
        SortChildren(roots);
        foreach (var node in folderNodes.Values)
            SortChildren(node.Children);

        _treeRoots = roots;
    }

    private static void SortChildren(List<TmplNode> children)
    {
        children.Sort((a, b) =>
        {
            var kindOrder = (int)a.Kind - (int)b.Kind;
            if (kindOrder != 0) return kindOrder;
            return string.Compare(a.Label, b.Label, StringComparison.OrdinalIgnoreCase);
        });
    }

    private async Task SelectTemplate(int templateId)
    {
        try
        {
            _selectedTemplate = await TemplateEngineRepository.GetTemplateWithChildrenAsync(templateId)
                                ?? _templates.FirstOrDefault(t => t.Id == templateId);
            if (_selectedTemplate == null) return;

            _editName = _selectedTemplate.Name;
            _editDescription = _selectedTemplate.Description;
            _editParentId = _selectedTemplate.ParentTemplateId ?? 0;

            _attributes = (await TemplateEngineRepository.GetAttributesByTemplateIdAsync(templateId)).ToList();
            _alarms = (await TemplateEngineRepository.GetAlarmsByTemplateIdAsync(templateId)).ToList();
            _scripts = (await TemplateEngineRepository.GetScriptsByTemplateIdAsync(templateId)).ToList();
            _compositions = (await TemplateEngineRepository.GetCompositionsByTemplateIdAsync(templateId)).ToList();

            _validationResult = null;
        }
        catch (Exception ex)
        {
            _toast.ShowError($"Failed to load template: {ex.Message}");
        }
    }

    private TreeView<TmplNode> _tree = default!;

    // ---- Drag-and-drop state ----
    private (TmplNodeKind kind, int id)? _dragPayload;
    private string? _dragOverKey;

    private void OnDragStart(TmplNode node)
    {
        if (node.Kind == TmplNodeKind.Composition) return;
        _dragPayload = (node.Kind, node.EntityId);
    }

    private void OnDragEnd()
    {
        _dragPayload = null;
        _dragOverKey = null;
    }

    private void OnDragEnter(TmplNode targetFolder)
    {
        if (_dragPayload == null) return;
        if (targetFolder.Kind != TmplNodeKind.Folder) return;
        _dragOverKey = targetFolder.Key;
    }

    private void OnDragLeave(TmplNode targetFolder)
    {
        if (_dragOverKey == targetFolder.Key) _dragOverKey = null;
    }

    private async Task OnDrop(TmplNode targetFolder)
    {
        if (_dragPayload is not { } payload) return;
        if (targetFolder.Kind != TmplNodeKind.Folder) return;

        var user = await GetCurrentUserAsync();
        if (payload.kind == TmplNodeKind.Folder)
        {
            var result = await TemplateFolderService.MoveFolderAsync(payload.id, targetFolder.EntityId, user);
            if (result.IsFailure) _toast.ShowError(result.Error);
        }
        else if (payload.kind == TmplNodeKind.Template)
        {
            var result = await TemplateService.MoveTemplateAsync(payload.id, targetFolder.EntityId, user);
            if (result.IsFailure) _toast.ShowError(result.Error);
        }

        OnDragEnd();
        await LoadTemplatesAsync();
    }

    private async Task OnDropOnRoot()
    {
        if (_dragPayload is not { } payload) return;

        var user = await GetCurrentUserAsync();
        if (payload.kind == TmplNodeKind.Folder)
        {
            var result = await TemplateFolderService.MoveFolderAsync(payload.id, null, user);
            if (result.IsFailure) _toast.ShowError(result.Error);
        }
        else if (payload.kind == TmplNodeKind.Template)
        {
            var result = await TemplateService.MoveTemplateAsync(payload.id, null, user);
            if (result.IsFailure) _toast.ShowError(result.Error);
        }

        OnDragEnd();
        await LoadTemplatesAsync();
    }

    private RenderFragment RenderTemplateDetail() => __builder =>
    {
        <div class="d-flex justify-content-between align-items-center mb-3">
            <div>
                <h4 class="d-inline mb-0">@_selectedTemplate!.Name</h4>
                @if (_selectedTemplate.ParentTemplateId.HasValue)
                {
                    <span class="text-muted ms-2">inherits @(_templates.FirstOrDefault(t => t.Id == _selectedTemplate.ParentTemplateId)?.Name)</span>
                }
            </div>
            <div>
                <button class="btn btn-outline-info btn-sm me-1" @onclick="RunValidation" disabled="@_validating">
                    @if (_validating)
                    {
                        <span class="spinner-border spinner-border-sm me-1"></span>
                    }
                    Validate
                </button>
            </div>
        </div>

        @* Validation results *@
        @if (_validationResult != null)
        {
            <div class="mb-3">
                @if (_validationResult.Errors.Count > 0)
                {
                    <div class="alert alert-danger py-2">
                        <strong>Validation Errors (@_validationResult.Errors.Count)</strong>
                        <ul class="mb-0 small">
                            @foreach (var err in _validationResult.Errors)
                            {
                                <li>[@err.Category] @err.Message @(err.EntityName != null ? $"({err.EntityName})" : "")</li>
                            }
                        </ul>
                    </div>
                }
                @if (_validationResult.Warnings.Count > 0)
                {
                    <div class="alert alert-warning py-2">
                        <strong>Warnings (@_validationResult.Warnings.Count)</strong>
                        <ul class="mb-0 small">
                            @foreach (var warn in _validationResult.Warnings)
                            {
                                <li>[@warn.Category] @warn.Message</li>
                            }
                        </ul>
                    </div>
                }
                @if (_validationResult.Errors.Count == 0 && _validationResult.Warnings.Count == 0)
                {
                    <div class="alert alert-success py-2">Validation passed with no errors or warnings.</div>
                }
            </div>
        }

        @* Template info edit *@
        <div class="card mb-3">
            <div class="card-header">Template Properties</div>
            <div class="card-body">
                <div class="row g-2 align-items-end">
                    <div class="col-md-3">
                        <label class="form-label small">Name</label>
                        <input type="text" class="form-control form-control-sm" @bind="_editName" />
                    </div>
                    <div class="col-md-4">
                        <label class="form-label small">Description</label>
                        <input type="text" class="form-control form-control-sm" @bind="_editDescription" />
                    </div>
                    <div class="col-md-3">
                        <label class="form-label small">Parent Template</label>
                        <select class="form-select form-select-sm" @bind="_editParentId">
                            <option value="0">(None)</option>
                            @foreach (var t in _templates.Where(t => t.Id != _selectedTemplate.Id))
                            {
                                <option value="@t.Id">@t.Name</option>
                            }
                        </select>
                    </div>
                    <div class="col-md-2">
                        <button class="btn btn-primary btn-sm" @onclick="UpdateTemplateProperties">Save Properties</button>
                    </div>
                </div>
            </div>
        </div>

        @* Tabs: Attributes, Alarms, Scripts, Compositions *@
        <ul class="nav nav-tabs mb-3">
            <li class="nav-item">
                <button class="nav-link @(_activeTab == "attributes" ? "active" : "")" @onclick='() => _activeTab = "attributes"'>
                    Attributes <span class="badge bg-secondary">@_attributes.Count</span>
                </button>
            </li>
            <li class="nav-item">
                <button class="nav-link @(_activeTab == "alarms" ? "active" : "")" @onclick='() => _activeTab = "alarms"'>
                    Alarms <span class="badge bg-secondary">@_alarms.Count</span>
                </button>
            </li>
            <li class="nav-item">
                <button class="nav-link @(_activeTab == "scripts" ? "active" : "")" @onclick='() => _activeTab = "scripts"'>
                    Scripts <span class="badge bg-secondary">@_scripts.Count</span>
                </button>
            </li>
            <li class="nav-item">
                <button class="nav-link @(_activeTab == "compositions" ? "active" : "")" @onclick='() => _activeTab = "compositions"'>
                    Compositions <span class="badge bg-secondary">@_compositions.Count</span>
                </button>
            </li>
        </ul>

        @if (_activeTab == "attributes")
        {
            @RenderAttributesTab()
        }
        else if (_activeTab == "alarms")
        {
            @RenderAlarmsTab()
        }
        else if (_activeTab == "scripts")
        {
            @RenderScriptsTab()
        }
        else if (_activeTab == "compositions")
        {
            @RenderCompositionsTab()
        }
    };

    private RenderFragment RenderNodeLabel(TmplNode node) => __builder =>
    {
        var draggable = node.Kind != TmplNodeKind.Composition;
        var isDropTarget = node.Kind == TmplNodeKind.Folder;
        var classes = "d-inline-block " + (_dragOverKey == node.Key ? "bg-info bg-opacity-25" : "");
        var style = node.Kind == TmplNodeKind.Composition && _dragPayload != null
            ? "opacity: 0.5;" : "";

        <div class="@classes" style="@style"
             draggable="@(draggable ? "true" : "false")"
             @ondragstart="() => OnDragStart(node)"
             @ondragend="OnDragEnd"
             @ondragenter="() => OnDragEnter(node)"
             @ondragleave="() => OnDragLeave(node)"
             @ondragover:preventDefault="@isDropTarget"
             @ondrop="() => OnDrop(node)"
             @ondrop:stopPropagation="true">
            @switch (node.Kind)
            {
                case TmplNodeKind.Folder:
                    <span class="me-1">📁</span>
                    <span>@node.Label</span>
                    <span class="badge bg-light text-dark ms-2">@node.Children.Count</span>
                    break;
                case TmplNodeKind.Template:
                    <strong>@node.Label</strong>
                    if (node.Template?.ParentTemplateId is int pid)
                    {
                        <span class="text-muted small ms-1">inherits @(_templates.FirstOrDefault(t => t.Id == pid)?.Name)</span>
                    }
                    <span class="badge bg-light text-dark ms-2">
                        @node.Template!.Attributes.Count attr,
                        @node.Template.Alarms.Count alm,
                        @node.Template.Scripts.Count scr
                    </span>
                    if (node.Template.Compositions.Count > 0)
                    {
                        <span class="badge bg-info text-dark ms-1">@node.Template.Compositions.Count comp</span>
                    }
                    break;
                case TmplNodeKind.Composition:
                    var composedName = _templates.FirstOrDefault(t => t.Id == node.Composition!.ComposedTemplateId)?.Name
                                       ?? $"#{node.Composition!.ComposedTemplateId}";
                    <span>@node.Label</span>
                    <span class="text-muted small ms-1">→ @composedName</span>
                    break;
            }
        </div>
    };

    private async Task OnTreeNodeSelected(object? key)
    {
        if (key is not string s) return;
        if (s.StartsWith("t:") && int.TryParse(s[2..], out var tid))
        {
            await SelectTemplate(tid);
        }
        else if (s.StartsWith("c:") && int.TryParse(s[2..], out var cid))
        {
            var comp = _templates.SelectMany(t => t.Compositions).FirstOrDefault(c => c.Id == cid);
            if (comp != null)
            {
                // Reveal + select the composed template.
                await _tree.RevealNode($"t:{comp.ComposedTemplateId}", select: true);
                await SelectTemplate(comp.ComposedTemplateId);
            }
        }
        // Folder selection: no-op (Section 4 design — folder click does not load detail).
    }

    private RenderFragment RenderNodeContextMenu(TmplNode node) => __builder =>
    {
        switch (node.Kind)
        {
            case TmplNodeKind.Folder:
                <button class="dropdown-item" @onclick="() => OpenNewFolderDialog(node.EntityId)">New Folder</button>
                <button class="dropdown-item" @onclick="() => OpenNewTemplateDialog(node.EntityId)">New Template</button>
                <button class="dropdown-item" @onclick="() => OpenRenameFolderDialog(node.EntityId, node.Label)">Rename</button>
                <div class="dropdown-divider"></div>
                <button class="dropdown-item text-danger" @onclick="() => DeleteFolder(node.EntityId, node.Label)">Delete</button>
                break;

            case TmplNodeKind.Template:
                <button class="dropdown-item" @onclick="() => SelectTemplate(node.EntityId)">Edit</button>
                <button class="dropdown-item" @onclick="() => OpenMoveTemplateDialog(node.EntityId, node.Label)">Move to Folder…</button>
                <div class="dropdown-divider"></div>
                <button class="dropdown-item text-danger" @onclick="() => DeleteTemplate(node.Template!)">Delete</button>
                break;

            case TmplNodeKind.Composition:
                var composedKey = $"t:{node.Composition!.ComposedTemplateId}";
                <button class="dropdown-item" @onclick="() => OnTreeNodeSelected(composedKey)">Open composed template</button>
                <button class="dropdown-item text-danger" @onclick="() => DeleteComposition(node.Composition)">Remove composition</button>
                break;
        }
    };

    // New-folder dialog state
    private bool _showNewFolderDialog;
    private int? _newFolderParentId;
    private string? _newFolderError;

    private void OpenNewFolderDialog(int? parentFolderId)
    {
        _newFolderParentId = parentFolderId;
        _newFolderError = null;
        _showNewFolderDialog = true;
    }

    private async Task SubmitNewFolder((int? ParentFolderId, string Name) req)
    {
        _newFolderError = null;
        var user = await GetCurrentUserAsync();
        var result = await TemplateFolderService.CreateFolderAsync(req.Name, req.ParentFolderId, user);
        if (result.IsSuccess)
        {
            _showNewFolderDialog = false;
            _toast.ShowSuccess($"Folder '{result.Value.Name}' created.");
            await LoadTemplatesAsync();
        }
        else
        {
            _newFolderError = result.Error;
        }
    }

    // New-template dialog state
    private bool _showNewTemplateDialog;
    private int? _newTemplateFolderId;
    private string? _newTemplateError;

    private void OpenNewTemplateDialog(int? folderId)
    {
        _newTemplateFolderId = folderId;
        _newTemplateError = null;
        _showNewTemplateDialog = true;
    }

    private async Task SubmitNewTemplate((int? FolderId, string Name, string? Description) req)
    {
        _newTemplateError = null;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.CreateTemplateAsync(
            req.Name, req.Description, null, user, folderId: req.FolderId);
        if (result.IsSuccess)
        {
            _showNewTemplateDialog = false;
            _toast.ShowSuccess($"Template '{result.Value.Name}' created.");
            await LoadTemplatesAsync();
            await SelectTemplate(result.Value.Id);
        }
        else
        {
            _newTemplateError = result.Error;
        }
    }

    // Move-template dialog state
    private bool _showMoveTemplateDialog;
    private int _moveTemplateId;
    private string _moveTemplateName = string.Empty;
    private string? _moveTemplateError;

    private void OpenMoveTemplateDialog(int templateId, string label)
    {
        _moveTemplateId = templateId;
        _moveTemplateName = label;
        _moveTemplateError = null;
        _showMoveTemplateDialog = true;
    }

    private async Task SubmitMoveTemplate((int TemplateId, int? NewFolderId) req)
    {
        _moveTemplateError = null;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.MoveTemplateAsync(req.TemplateId, req.NewFolderId, user);
        if (result.IsSuccess)
        {
            _showMoveTemplateDialog = false;
            _toast.ShowSuccess($"Template '{_moveTemplateName}' moved.");
            await LoadTemplatesAsync();
        }
        else
        {
            _moveTemplateError = result.Error;
        }
    }

    // Flat list of folders with indentation labels, for the picker.
    private IEnumerable<(int? Id, string Label)> EnumerateFolderOptions()
    {
        yield return (null, "(Root)");
        foreach (var f in WalkFolderHierarchy(_folders.Where(f => f.ParentFolderId == null), 0))
            yield return f;
    }

    private IEnumerable<(int? Id, string Label)> WalkFolderHierarchy(IEnumerable<TemplateFolder> level, int depth)
    {
        foreach (var f in level.OrderBy(f => f.Name, StringComparer.OrdinalIgnoreCase))
        {
            yield return ((int?)f.Id, new string(' ', depth * 2) + f.Name);
            foreach (var sub in WalkFolderHierarchy(_folders.Where(c => c.ParentFolderId == f.Id), depth + 1))
                yield return sub;
        }
    }

    // Rename folder dialog state
    private bool _showRenameFolderDialog;
    private int _renameFolderId;
    private string _renameFolderInitialName = string.Empty;
    private string? _renameFolderError;

    private void OpenRenameFolderDialog(int folderId, string currentName)
    {
        _renameFolderId = folderId;
        _renameFolderInitialName = currentName;
        _renameFolderError = null;
        _showRenameFolderDialog = true;
    }

    private async Task SubmitRenameFolder((int FolderId, string NewName) req)
    {
        _renameFolderError = null;
        var user = await GetCurrentUserAsync();
        var result = await TemplateFolderService.RenameFolderAsync(req.FolderId, req.NewName, user);
        if (result.IsSuccess)
        {
            _showRenameFolderDialog = false;
            _toast.ShowSuccess("Folder renamed.");
            await LoadTemplatesAsync();
        }
        else
        {
            _renameFolderError = result.Error;
        }
    }

    private async Task DeleteFolder(int folderId, string label)
    {
        var confirmed = await _confirmDialog.ShowAsync($"Delete folder '{label}'?", "Delete Folder");
        if (!confirmed) return;

        var user = await GetCurrentUserAsync();
        var result = await TemplateFolderService.DeleteFolderAsync(folderId, user);
        if (result.IsSuccess)
        {
            _toast.ShowSuccess($"Folder '{label}' deleted.");
            await LoadTemplatesAsync();
        }
        else
        {
            _toast.ShowError(result.Error);
        }
    }

    private async Task DeleteTemplate(Template template)
    {
        var confirmed = await _confirmDialog.ShowAsync(
            $"Delete template '{template.Name}'? This will fail if instances or child templates reference it.",
            "Delete Template");
        if (!confirmed) return;

        try
        {
            var user = await GetCurrentUserAsync();
            var result = await TemplateService.DeleteTemplateAsync(template.Id, user);
            if (result.IsSuccess)
            {
                _toast.ShowSuccess($"Template '{template.Name}' deleted.");
                await LoadTemplatesAsync();
            }
            else
            {
                _toast.ShowError(result.Error);
            }
        }
        catch (Exception ex)
        {
            _toast.ShowError($"Delete failed: {ex.Message}");
        }
    }

    private async Task UpdateTemplateProperties()
    {
        if (_selectedTemplate == null) return;
        try
        {
            var user = await GetCurrentUserAsync();
            var result = await TemplateService.UpdateTemplateAsync(
                _selectedTemplate.Id, _editName.Trim(), _editDescription?.Trim(),
                _editParentId == 0 ? null : _editParentId, user);

            if (result.IsSuccess)
            {
                _toast.ShowSuccess("Template properties updated.");
                await LoadTemplatesAsync();
                _selectedTemplate = result.Value;
            }
            else
            {
                _toast.ShowError(result.Error);
            }
        }
        catch (Exception ex)
        {
            _toast.ShowError($"Update failed: {ex.Message}");
        }
    }

    private async Task RunValidation()
    {
        if (_selectedTemplate == null) return;
        _validating = true;
        _validationResult = null;
        try
        {
            // Use the full validation pipeline via TemplateService
            // This performs flattening, collision detection, script compilation,
            // trigger reference validation, and connection binding checks
            var validationService = new ValidationService();
            var flatConfig = new Commons.Types.Flattening.FlattenedConfiguration
            {
                InstanceUniqueName = $"validation-{_selectedTemplate.Name}",
                TemplateId = _selectedTemplate.Id,
                Attributes = _attributes.Select(a => new Commons.Types.Flattening.ResolvedAttribute
                {
                    CanonicalName = a.Name,
                    Value = a.Value,
                    DataType = a.DataType.ToString(),
                    IsLocked = a.IsLocked,
                    DataSourceReference = a.DataSourceReference
                }).ToList(),
                Alarms = _alarms.Select(a => new Commons.Types.Flattening.ResolvedAlarm
                {
                    CanonicalName = a.Name,
                    PriorityLevel = a.PriorityLevel,
                    IsLocked = a.IsLocked,
                    TriggerType = a.TriggerType.ToString(),
                    TriggerConfiguration = a.TriggerConfiguration
                }).ToList(),
                Scripts = _scripts.Select(s => new Commons.Types.Flattening.ResolvedScript
                {
                    CanonicalName = s.Name,
                    Code = s.Code,
                    IsLocked = s.IsLocked,
                    TriggerType = s.TriggerType,
                    TriggerConfiguration = s.TriggerConfiguration,
                    ParameterDefinitions = s.ParameterDefinitions,
                    ReturnDefinition = s.ReturnDefinition
                }).ToList()
            };
            _validationResult = validationService.Validate(flatConfig);

            // Also check for naming collisions across the inheritance/composition graph
            var collisions = await TemplateService.DetectCollisionsAsync(_selectedTemplate.Id);
            if (collisions.Count > 0)
            {
                var collisionErrors = collisions.Select(c =>
                    Commons.Types.Flattening.ValidationEntry.Error(
                        Commons.Types.Flattening.ValidationCategory.NamingCollision, c)).ToArray();
                var collisionResult = new Commons.Types.Flattening.ValidationResult { Errors = collisionErrors };
                _validationResult = Commons.Types.Flattening.ValidationResult.Merge(_validationResult, collisionResult);
            }
        }
        catch (Exception ex)
        {
            _toast.ShowError($"Validation error: {ex.Message}");
        }
        _validating = false;
    }

    // ---- Attributes Tab ----
    private RenderFragment RenderAttributesTab() => __builder =>
    {
        <div class="d-flex justify-content-between align-items-center mb-2">
            <h6 class="mb-0">Attributes</h6>
            <button class="btn btn-primary btn-sm" @onclick="() => { _showAttrForm = true; _attrFormError = null; _attrName = string.Empty; _attrValue = null; _attrIsLocked = false; _attrDataSourceRef = null; }">Add Attribute</button>
        </div>

        @if (_showAttrForm)
        {
            <div class="card mb-2">
                <div class="card-body">
                    <div class="row g-2 align-items-end">
                        <div class="col-md-2">
                            <label class="form-label small">Name</label>
                            <input type="text" class="form-control form-control-sm" @bind="_attrName" />
                        </div>
                        <div class="col-md-2">
                            <label class="form-label small">Data Type</label>
                            <select class="form-select form-select-sm" @bind="_attrDataType">
                                @foreach (var dt in Enum.GetValues<DataType>())
                                {
                                    <option value="@dt">@dt</option>
                                }
                            </select>
                        </div>
                        <div class="col-md-2">
                            <label class="form-label small">Value</label>
                            <input type="text" class="form-control form-control-sm" @bind="_attrValue" />
                        </div>
                        <div class="col-md-2">
                            <label class="form-label small">Data Source Ref</label>
                            <input type="text" class="form-control form-control-sm" @bind="_attrDataSourceRef" placeholder="Tag path" />
                        </div>
                        <div class="col-md-1">
                            <div class="form-check">
                                <input class="form-check-input" type="checkbox" @bind="_attrIsLocked" id="attrLocked" />
                                <label class="form-check-label small" for="attrLocked">Locked</label>
                            </div>
                        </div>
                        <div class="col-md-3">
                            <button class="btn btn-success btn-sm me-1" @onclick="AddAttribute">Add</button>
                            <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showAttrForm = false">Cancel</button>
                        </div>
                    </div>
                    @if (_attrFormError != null) { <div class="text-danger small mt-1">@_attrFormError</div> }
                </div>
            </div>
        }

        <table class="table table-sm table-striped">
            <thead class="table-light">
                <tr>
                    <th>Name</th>
                    <th>Type</th>
                    <th>Value</th>
                    <th>Data Source</th>
                    <th>Lock</th>
                    <th style="width: 80px;">Actions</th>
                </tr>
            </thead>
            <tbody>
                @foreach (var attr in _attributes)
                {
                    <tr>
                        <td>@attr.Name</td>
                        <td><span class="badge bg-light text-dark">@attr.DataType</span></td>
                        <td class="small">@(attr.Value ?? "—")</td>
                        <td class="small text-muted">@(attr.DataSourceReference ?? "—")</td>
                        <td>
                            @if (attr.IsLocked)
                            {
                                <span class="badge bg-danger" title="Locked">L</span>
                            }
                            else
                            {
                                <span class="badge bg-light text-dark" title="Unlocked">U</span>
                            }
                        </td>
                        <td>
                            <button class="btn btn-outline-danger btn-sm py-0 px-1"
                                    @onclick="() => DeleteAttribute(attr)">Delete</button>
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    };

    // ---- Alarms Tab ----
    private RenderFragment RenderAlarmsTab() => __builder =>
    {
        <div class="d-flex justify-content-between align-items-center mb-2">
            <h6 class="mb-0">Alarms</h6>
            <button class="btn btn-primary btn-sm" @onclick="() => { _showAlarmForm = true; _alarmFormError = null; _alarmName = string.Empty; _alarmPriority = 500; _alarmTriggerConfig = null; _alarmIsLocked = false; }">Add Alarm</button>
        </div>

        @if (_showAlarmForm)
        {
            <div class="card mb-2">
                <div class="card-body">
                    <div class="row g-2 align-items-end">
                        <div class="col-md-2">
                            <label class="form-label small">Name</label>
                            <input type="text" class="form-control form-control-sm" @bind="_alarmName" />
                        </div>
                        <div class="col-md-2">
                            <label class="form-label small">Trigger Type</label>
                            <select class="form-select form-select-sm" @bind="_alarmTriggerType">
                                @foreach (var tt in Enum.GetValues<AlarmTriggerType>())
                                {
                                    <option value="@tt">@tt</option>
                                }
                            </select>
                        </div>
                        <div class="col-md-1">
                            <label class="form-label small">Priority</label>
                            <input type="number" class="form-control form-control-sm" @bind="_alarmPriority" min="0" max="1000" />
                        </div>
                        <div class="col-md-3">
                            <label class="form-label small">Trigger Config (JSON)</label>
                            <input type="text" class="form-control form-control-sm" @bind="_alarmTriggerConfig" />
                        </div>
                        <div class="col-md-1">
                            <div class="form-check">
                                <input class="form-check-input" type="checkbox" @bind="_alarmIsLocked" id="alarmLocked" />
                                <label class="form-check-label small" for="alarmLocked">Locked</label>
                            </div>
                        </div>
                        <div class="col-md-3">
                            <button class="btn btn-success btn-sm me-1" @onclick="AddAlarm">Add</button>
                            <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showAlarmForm = false">Cancel</button>
                        </div>
                    </div>
                    @if (_alarmFormError != null) { <div class="text-danger small mt-1">@_alarmFormError</div> }
                </div>
            </div>
        }

        <table class="table table-sm table-striped">
            <thead class="table-light">
                <tr>
                    <th>Name</th>
                    <th>Trigger</th>
                    <th>Priority</th>
                    <th>Config</th>
                    <th>Lock</th>
                    <th style="width: 80px;">Actions</th>
                </tr>
            </thead>
            <tbody>
                @foreach (var alarm in _alarms)
                {
                    <tr>
                        <td>@alarm.Name</td>
                        <td><span class="badge bg-light text-dark">@alarm.TriggerType</span></td>
                        <td>@alarm.PriorityLevel</td>
                        <td class="small text-muted text-truncate" style="max-width: 200px;">@(alarm.TriggerConfiguration ?? "—")</td>
                        <td>
                            @if (alarm.IsLocked) { <span class="badge bg-danger">L</span> }
                            else { <span class="badge bg-light text-dark">U</span> }
                        </td>
                        <td>
                            <button class="btn btn-outline-danger btn-sm py-0 px-1"
                                    @onclick="() => DeleteAlarm(alarm)">Delete</button>
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    };

    // ---- Scripts Tab ----
    private RenderFragment RenderScriptsTab() => __builder =>
    {
        <div class="d-flex justify-content-between align-items-center mb-2">
            <h6 class="mb-0">Scripts</h6>
            <button class="btn btn-primary btn-sm" @onclick="() => { _showScriptForm = true; _scriptFormError = null; _scriptName = string.Empty; _scriptCode = string.Empty; _scriptTriggerType = null; _scriptTriggerConfig = null; _scriptIsLocked = false; }">Add Script</button>
        </div>

        @if (_showScriptForm)
        {
            <div class="card mb-2">
                <div class="card-body">
                    <div class="row g-2">
                        <div class="col-md-3">
                            <label class="form-label small">Name</label>
                            <input type="text" class="form-control form-control-sm" @bind="_scriptName" />
                        </div>
                        <div class="col-md-2">
                            <label class="form-label small">Trigger Type</label>
                            <input type="text" class="form-control form-control-sm" @bind="_scriptTriggerType" placeholder="e.g. ValueChange" />
                        </div>
                        <div class="col-md-3">
                            <label class="form-label small">Trigger Config (JSON)</label>
                            <input type="text" class="form-control form-control-sm" @bind="_scriptTriggerConfig" />
                        </div>
                        <div class="col-md-1">
                            <div class="form-check mt-4">
                                <input class="form-check-input" type="checkbox" @bind="_scriptIsLocked" id="scriptLocked" />
                                <label class="form-check-label small" for="scriptLocked">Locked</label>
                            </div>
                        </div>
                    </div>
                    <div class="mt-2">
                        <label class="form-label small">Code</label>
                        <textarea class="form-control form-control-sm font-monospace" rows="6" @bind="_scriptCode"
                                  style="font-size: 0.8rem;"></textarea>
                    </div>
                    <div class="mt-2">
                        <button class="btn btn-success btn-sm me-1" @onclick="AddScript">Add</button>
                        <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showScriptForm = false">Cancel</button>
                    </div>
                    @if (_scriptFormError != null) { <div class="text-danger small mt-1">@_scriptFormError</div> }
                </div>
            </div>
        }

        <table class="table table-sm table-striped">
            <thead class="table-light">
                <tr>
                    <th>Name</th>
                    <th>Trigger</th>
                    <th>Code (preview)</th>
                    <th>Lock</th>
                    <th style="width: 80px;">Actions</th>
                </tr>
            </thead>
            <tbody>
                @foreach (var script in _scripts)
                {
                    <tr>
                        <td>@script.Name</td>
                        <td class="small">@(script.TriggerType ?? "—")</td>
                        <td class="small text-muted text-truncate font-monospace" style="max-width: 300px;">@script.Code[..Math.Min(80, script.Code.Length)]@(script.Code.Length > 80 ? "..." : "")</td>
                        <td>
                            @if (script.IsLocked) { <span class="badge bg-danger">L</span> }
                            else { <span class="badge bg-light text-dark">U</span> }
                        </td>
                        <td>
                            <button class="btn btn-outline-danger btn-sm py-0 px-1"
                                    @onclick="() => DeleteScript(script)">Delete</button>
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    };

    // ---- Compositions Tab ----
    private RenderFragment RenderCompositionsTab() => __builder =>
    {
        <div class="d-flex justify-content-between align-items-center mb-2">
            <h6 class="mb-0">Compositions</h6>
            <button class="btn btn-primary btn-sm" @onclick="() => { _showCompForm = true; _compFormError = null; _compInstanceName = string.Empty; _compComposedTemplateId = 0; }">Add Composition</button>
        </div>

        @if (_showCompForm)
        {
            <div class="card mb-2">
                <div class="card-body">
                    <div class="row g-2 align-items-end">
                        <div class="col-md-3">
                            <label class="form-label small">Instance Name</label>
                            <input type="text" class="form-control form-control-sm" @bind="_compInstanceName" />
                        </div>
                        <div class="col-md-4">
                            <label class="form-label small">Composed Template</label>
                            <select class="form-select form-select-sm" @bind="_compComposedTemplateId">
                                <option value="0">Select template...</option>
                                @foreach (var t in _templates.Where(t => _selectedTemplate == null || t.Id != _selectedTemplate.Id))
                                {
                                    <option value="@t.Id">@t.Name</option>
                                }
                            </select>
                        </div>
                        <div class="col-md-3">
                            <button class="btn btn-success btn-sm me-1" @onclick="AddComposition">Add</button>
                            <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showCompForm = false">Cancel</button>
                        </div>
                    </div>
                    @if (_compFormError != null) { <div class="text-danger small mt-1">@_compFormError</div> }
                </div>
            </div>
        }

        <table class="table table-sm table-striped">
            <thead class="table-light">
                <tr>
                    <th>Instance Name</th>
                    <th>Composed Template</th>
                    <th style="width: 80px;">Actions</th>
                </tr>
            </thead>
            <tbody>
                @foreach (var comp in _compositions)
                {
                    <tr>
                        <td><code>@comp.InstanceName</code></td>
                        <td>@(_templates.FirstOrDefault(t => t.Id == comp.ComposedTemplateId)?.Name ?? $"#{comp.ComposedTemplateId}")</td>
                        <td>
                            <button class="btn btn-outline-danger btn-sm py-0 px-1"
                                    @onclick="() => DeleteComposition(comp)">Delete</button>
                        </td>
                    </tr>
                }
            </tbody>
        </table>
    };

    // ---- CRUD handlers ----

    private async Task AddAttribute()
    {
        if (_selectedTemplate == null) return;
        _attrFormError = null;
        if (string.IsNullOrWhiteSpace(_attrName)) { _attrFormError = "Name is required."; return; }

        var attr = new TemplateAttribute(_attrName.Trim())
        {
            DataType = _attrDataType,
            Value = _attrValue?.Trim(),
            IsLocked = _attrIsLocked,
            DataSourceReference = _attrDataSourceRef?.Trim()
        };

        var user = await GetCurrentUserAsync();
        var result = await TemplateService.AddAttributeAsync(_selectedTemplate.Id, attr, user);
        if (result.IsSuccess)
        {
            _showAttrForm = false;
            _toast.ShowSuccess($"Attribute '{_attrName}' added.");
            await SelectTemplate(_selectedTemplate.Id);
        }
        else
        {
            _attrFormError = result.Error;
        }
    }

    private async Task DeleteAttribute(TemplateAttribute attr)
    {
        var confirmed = await _confirmDialog.ShowAsync($"Delete attribute '{attr.Name}'?", "Delete Attribute");
        if (!confirmed) return;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.DeleteAttributeAsync(attr.Id, user);
        if (result.IsSuccess)
        {
            _toast.ShowSuccess($"Attribute '{attr.Name}' deleted.");
            if (_selectedTemplate != null) await SelectTemplate(_selectedTemplate.Id);
        }
        else
        {
            _toast.ShowError(result.Error);
        }
    }

    private async Task AddAlarm()
    {
        if (_selectedTemplate == null) return;
        _alarmFormError = null;
        if (string.IsNullOrWhiteSpace(_alarmName)) { _alarmFormError = "Name is required."; return; }

        var alarm = new TemplateAlarm(_alarmName.Trim())
        {
            TriggerType = _alarmTriggerType,
            PriorityLevel = _alarmPriority,
            TriggerConfiguration = _alarmTriggerConfig?.Trim(),
            IsLocked = _alarmIsLocked
        };

        var user = await GetCurrentUserAsync();
        var result = await TemplateService.AddAlarmAsync(_selectedTemplate.Id, alarm, user);
        if (result.IsSuccess)
        {
            _showAlarmForm = false;
            _toast.ShowSuccess($"Alarm '{_alarmName}' added.");
            await SelectTemplate(_selectedTemplate.Id);
        }
        else
        {
            _alarmFormError = result.Error;
        }
    }

    private async Task DeleteAlarm(TemplateAlarm alarm)
    {
        var confirmed = await _confirmDialog.ShowAsync($"Delete alarm '{alarm.Name}'?", "Delete Alarm");
        if (!confirmed) return;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.DeleteAlarmAsync(alarm.Id, user);
        if (result.IsSuccess)
        {
            _toast.ShowSuccess($"Alarm '{alarm.Name}' deleted.");
            if (_selectedTemplate != null) await SelectTemplate(_selectedTemplate.Id);
        }
        else { _toast.ShowError(result.Error); }
    }

    private async Task AddScript()
    {
        if (_selectedTemplate == null) return;
        _scriptFormError = null;
        if (string.IsNullOrWhiteSpace(_scriptName)) { _scriptFormError = "Name is required."; return; }
        if (string.IsNullOrWhiteSpace(_scriptCode)) { _scriptFormError = "Code is required."; return; }

        var script = new TemplateScript(_scriptName.Trim(), _scriptCode)
        {
            TriggerType = _scriptTriggerType?.Trim(),
            TriggerConfiguration = _scriptTriggerConfig?.Trim(),
            IsLocked = _scriptIsLocked
        };

        var user = await GetCurrentUserAsync();
        var result = await TemplateService.AddScriptAsync(_selectedTemplate.Id, script, user);
        if (result.IsSuccess)
        {
            _showScriptForm = false;
            _toast.ShowSuccess($"Script '{_scriptName}' added.");
            await SelectTemplate(_selectedTemplate.Id);
        }
        else
        {
            _scriptFormError = result.Error;
        }
    }

    private async Task DeleteScript(TemplateScript script)
    {
        var confirmed = await _confirmDialog.ShowAsync($"Delete script '{script.Name}'?", "Delete Script");
        if (!confirmed) return;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.DeleteScriptAsync(script.Id, user);
        if (result.IsSuccess)
        {
            _toast.ShowSuccess($"Script '{script.Name}' deleted.");
            if (_selectedTemplate != null) await SelectTemplate(_selectedTemplate.Id);
        }
        else { _toast.ShowError(result.Error); }
    }

    private async Task AddComposition()
    {
        if (_selectedTemplate == null) return;
        _compFormError = null;
        if (string.IsNullOrWhiteSpace(_compInstanceName)) { _compFormError = "Instance name is required."; return; }
        if (_compComposedTemplateId == 0) { _compFormError = "Select a template."; return; }

        var user = await GetCurrentUserAsync();
        var result = await TemplateService.AddCompositionAsync(
            _selectedTemplate.Id, _compComposedTemplateId, _compInstanceName.Trim(), user);
        if (result.IsSuccess)
        {
            _showCompForm = false;
            _toast.ShowSuccess($"Composition '{_compInstanceName}' added.");
            await SelectTemplate(_selectedTemplate.Id);
        }
        else
        {
            _compFormError = result.Error;
        }
    }

    private async Task DeleteComposition(TemplateComposition comp)
    {
        var confirmed = await _confirmDialog.ShowAsync($"Remove composition '{comp.InstanceName}'?", "Delete Composition");
        if (!confirmed) return;
        var user = await GetCurrentUserAsync();
        var result = await TemplateService.DeleteCompositionAsync(comp.Id, user);
        if (result.IsSuccess)
        {
            _toast.ShowSuccess($"Composition '{comp.InstanceName}' removed.");
            if (_selectedTemplate != null) await SelectTemplate(_selectedTemplate.Id);
        }
        else { _toast.ShowError(result.Error); }
    }
}